1/*******************************************************************************
2 *
3 * Copyright (c) 1993 Intel Corporation
4 *
5 * Intel hereby grants you permission to copy, modify, and distribute this
6 * software and its documentation.  Intel grants this permission provided
7 * that the above copyright notice appears in all copies and that both the
8 * copyright notice and this permission notice appear in supporting
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10 * you prominently mark as "not part of the original" any modifications
11 * made to this software or documentation, and that the name of Intel
12 * Corporation not be used in advertising or publicity pertaining to
13 * distribution of the software or the documentation without specific,
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17 * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
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29 ******************************************************************************/
30
31	.file "strch_ca.s"
32#ifdef	__PIC
33	.pic
34#endif
35#ifdef	__PID
36	.pid
37#endif
38/*
39 * (c) copyright 1988,1993 Intel Corp., all rights reserved
40 */
41
42/*
43	procedure strchr  (optimized assembler version for the CA)
44
45	src_addr = strchr (src_addr, char)
46
47	return a pointer to the first byte that contains the indicated
48	byte in the source string.  Return null if the byte is not found.
49
50	Undefined behavior will occur if the end of the source string (i.e.
51	the terminating null byte) is in the last two words of the program's
52	allocated memory space.  This is so because, in several cases, strchr
53	will fetch ahead.  Disallowing the fetch ahead would impose a severe
54	performance penalty.
55
56	This program handles two cases:
57
58	1) the argument starts on a word boundary
59	2) the argument doesn't start on a word boundary
60
61	At the time of this writing, only g0 thru g7 and g13 are available
62	for use in this leafproc;  other registers would have to be saved and
63	restored.  These nine registers, plus tricky use of g14 are sufficient
64	to implement the routine.  The registers are used as follows:
65
66	g0  src ptr;  upon return it is a pointer to the matching byte, or null
67	g1  char to seek
68	g2  mask to avoid unimportant bytes in first word
69	g3  char to seek, broadcast to all four bytes
70	g4  word of the source string
71	g5  copy of the word
72	g6  extracted character
73	g7  byte extraction mask
74	g13 return address
75	g14
76*/
77
78	.globl	_strchr
79	.globl	__strchr
80	.leafproc	_strchr, __strchr
81	.align	2
82_strchr:
83#ifndef __PIC
84	lda 	Lrett,g14
85#else
86	lda 	Lrett-(.+8)(ip),g14
87#endif
88__strchr:
89
90	lda	0xff,g7		# byte extraction mask
91	and	g1,g7,g1	# make char an 8-bit ordinal
92	shlo	8,g1,g2		# broadcast the char to four bytes
93	or	g1,g2,g2
94	shlo	16,g2,g4
95	cmpo	g1,g7		# is char being sought 0xff?
96	or	g4,g2,g3
97	 lda	(g14),g13	# preserve return address
98	notand	g0,3,g5		# extract word addr of start of src
99	 lda	0,g14		# conform to register linkage standard
100	and	g0,3,g6		# extract byte offset of src
101	 ld	(g5),g4		# fetch word containing at least first byte
102	shlo	3,g6,g6		# get shift count for making mask for first word
103	 lda	4(g5),g0	# post-increment src word pointer
104	subi	1,0,g5		# mask initially all ones
105#if __i960_BIG_ENDIAN__
106	shro	g6,g5,g5	# get mask for bytes needed from first word
107#else
108	shlo	g6,g5,g5	# get mask for bytes needed from first word
109#endif
110	notor	g4,g5,g4	# set unneeded bytes to all ones
111	 be.f	Lsearch_for_0xff	# branch if seeking 0xff
112
113Lsearch_for_word_with_char_or_null:
114	scanbyte g3,g4		# check for byte with char
115	 lda	(g4),g5		# copy word
116	ld	(g0),g4		# fetch next word of src
117	 bo.f	Lsearch_for_char	# branch if null found
118	scanbyte 0,g5		# check for null byte
119	 lda	4(g0),g0	# post-increment src word pointer
120	bno.t	Lsearch_for_word_with_char_or_null	# branch if not null
121
122Lnot_found:
123	mov	0,g0		# char not found.  Return null
124Lexit_code:
125	bx	(g13)		# g0 = addr of char in src (or null);  g14 = 0
126Lrett:
127	ret
128
129Lsearch_for_char:
130	subo	5,g0,g0		# back up the byte pointer
131Lsearch_for_char.a:
132#if __i960_BIG_ENDIAN__
133	rotate	8,g5,g5		# shift word to position next byte
134#endif
135	and	g5,g7,g6	# extract byte
136	cmpo	g1,g6		# is it char?
137	 lda	1(g0),g0	# bump src byte ptr
138#if ! __i960_BIG_ENDIAN__
139	shro	8,g5,g5		# shift word to position next byte
140#endif
141	 be.f	Lexit_code
142	cmpobne.t 0,g6,Lsearch_for_char.a	# quit if null comes before char
143	b	Lnot_found
144
145Lsearch_for_0xff:
146	lda	0xf0f0f0f0,g2	# make first comparison mask for char=-1 case.
147	or	g5,g2,g2
148	and	g4,g2,g4	# make unimportant bytes of first word 0x0f
149	 b	Lsearch_for_word_with_char_or_null
150
151/* end of strchr */
152
153